Hot-air engine



- (No Model.) 2 Sheets-Sheen 1.

J. J. MOTIGHE. HOTAIR ENGINE. N 2 v Patented June 3, 1890.

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2Sheets-Sheet 2. J. J. McTIGHE.

- HOT. AIR ENGINE. No. 429,282.

Patented June 3, 1890.

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UNITED STATES PATENT FFICE.

JAMES J. MOTIGHE, OF PITTSBURG, PENNSYLVANIA.

HOT-AIR ENGINE.

SPECIFICATION forming part of Letters Patent No. 429,282, dated June 3, 1890.

' Application filed November 11, 1889. Serial No. 329,858. (No model.)

full, clear, and exact description of the in-- vention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to the construction and operation of hot-air engines, and is especially designed as an improvement upon that class of hot-air engines in which the power is obtained from the working body of air by introducing into it external sprays of hot and cold liquid. The thermo-dynamic principles upon which such a hot-air engine operates are fully set forth in United States Letters Patent No. 411,605, issued to me September 24, 1889, for the method of transforming heat energy into motive power, as also in my pending application, Serial No. 318,435, filed July 23, 1889, for improvements in hot-air engines. In my said patent and pending application I have shown how a greatly-increased efficiency of conversion can be obtained by avoiding the loss due to the latent heat of steam, seizing the advantages afforded by heating a highly-compressed body of air, gas, or vapor as the working-fluid and adopting as the heating medium abody whose surface can be made to vary between very wide limits.

The object of my present invention is threefold: First, to effect the cooling of the air by the cold spray in a separate chamber from that used in heating the air by the hot spray; second, to compound the engine, and thus obtain not only the full advantage of expansion as'a direct power, but also provide a means whereby the engine may secure its own source of cold, and, finally, to render the heater and cooler and working body of air independent of each other as to pressure, so as to permit a very high pressure to be maintained in the cylinder, while keeping the pressure in the heater and cooler down to such. limitations of strength and durability as are established by custom and law in the analogous construction of steam-boilers.

To these and other ends my present invention consists in the arrangement and combination of devices and instrumentalities, substantially as hereinafter fully described and claimed.

In the drawings which form part of this specification, Figure 1 is a vertical longitudinal section of the hot side of the engine on line a a, showing the working-cylinder and the pumping apparatus and valves interposed between the cylinder and the heater, which is not shown. Fig. 2 is a similar view of the cold side of the engine on line Z) b, with the parts occupying a position in working relation with the positions shown in Fig. I. Fig. 3' is a horizontal section of the high and low pressure cylinders and the interposed communication-valves. Fig. 4 is a transverse vertical section on the line 0 0, showing the relations of the different parts, the coldliquid passages being shown on the inner side of cylinder. Fig. 5 is a diagram showing the crank relations of the two pistons. Fig. 6 is a detail section of the pump, valves, and bypass slide by which automatic regulation of the hot and cold sprays is effected. Fig. 7 is an elevation of a modified arrangement of the various devices employed.

If the same chamber be used for heating and cooling alternately by throwing into it alternately hot and cold liquid, the theoretical efficiency cannot be reached in practice for the following reasons: The heated liquid strikes the cold-chamber walls, which, being of course constructed of metal and a good conductor of heat, take away a certain percentage of the dynamic value of the heat which exists in the hot liquid and which would otherwise be made available in maintaining the temperature of the working body of air. Moreover, these metal walls absorb a certain amount of heat from the vapor which is present in the air, and this has an indirect effect in chilling the air. Again the cooling effect of the cold liquid is prevented from reaching its full value because the metal walls have previously absorbed heat from the hot liquid and vapor, as above stated, and impart this or a part of this heat again to the next incoming cold liquid and the vapor present, thus preventing the designed extent in fall of temperature and sending heat uselessly to the cooler.

Referring now to the accompanying drawings, I avoid the foregoing difficulties and introduce many advantages by my improvements, which are carried into effect as follows:

II is the hot cylinder, and C is the cold cylinder, respectively provided with the pistons P and P which connect by means of the piston-rods 1 and 2 with a common shaft. At a convenient pointfor instance, above the cylinders-4 place a tank 3 for the storage of compressed air under a predetermined pressure, the air being forced into said tank by means of an air-pump, which is operated by an eccentric on the main shaft, as in my said patent and pending application. The purpose of the pump is to produce the initial pressure of air on both sides of the pistons in the two cylinders, and I prefer to arrange the tank 3 with a suitable capacity to supply anyleakage or reduction of pressure which may take place below the normal. I fit the tank 3 with a safety-valve 4-, of any of the wellknown forms, so as to blow off if the pressure in the tank exceeds a certain predetermined limit. The air-pum p is not shown, as the construction of such a device is well understood, and is clearly set forth in my said patent. For the purpose of the present application it is suffieicnt to assume that a suitable form of air-pump is arranged to deliver air under pressure into the tank 3. Air is admitted to cylinder by the pipe or pipes 17; its return prevented by check-valves v.

The two cylinders may conveniently be made in a single casting with the dividingwall elbetween them, and in this wall I construct the ports 5 and 6, and interpose therein the rotary communication valves 7 and S, which rotate on vertical axes. Valve 7 has the passage 9 corresponding to the ports 5, andvalve Shas the passage 10 corresponding with the ports 6. These rotary valves have their stems projecting upwardly, or downwardly, if preferred, and are operated by means of suitable connections with the main shaft. As their movement is an intermittent one, I prefer to place on the shaft cams of a proper form and. operate them from the cams.

Connecting with the hot cylinder 1-1 is the hot-water pump 11, which is made up of two cylinders, with the respective pistons 12 and 13 on a single piston-rod, which in turn is connected to an eccentric on the main shaft. The pump 11 has the lower ports 14, 15, 1G, and 17 arranged at the respective ends of the two pump-cylinders, and above has the corresponding ports 18, 19, 20, and 21. In these upper ports I interpose the piston-valve 22, whose stem 23 is also connected by suitable means to the main shaft and operated thereby. In the lower ports 14., 15, 16, and 17, I interpose a piston-valve 24, whose stem is likewise connected to and operated from the main shaft. th the piston-valves 22 and 24 are provided with ports so arranged that in one position of the valve 22 the ports 18 and 19 are open, while 20 and 21 are closed, and in the other position 20 and 21 are open, while 18 and 19 are closed. Piston-valve 24 is constructed in a similar manner. The upper port 18 leads directly to the hot-spray nozzle 26 and the port 21 to the hotspray nozzle 27, located in suitable positions in the ends of cylinder ll. Ports 1!) and 20 form the waste-ports and enter the respective ends of the cylinder II at the points 28 and 2!), as shown. The lower ports 14: and 17 connect with the heater, which is not shown in this case, as it may be of any suitable form, and the lower ports 15 and 16, for convenience, join together and are connected by a pipe with the heater, the ports 14 and 17 receiving hot water from the heater, and the ports 15 and 16 returning the spent hot water to the heater.

The cold cylinder 0 is arranged with a similarset of pumps and valves-namely, the pump-cylinders 30 31, pistons 33, rod 34:,

connected to the shaft by an eccentric or equivalent, upper ports 35, 36, 37, and 3S and lower ports 39, 40, 41, and .2, the interposed upper piston-valve 43 having its stem it connected to a cam on the main shaft and the lower piston-valve having its stem 16 also connected to a cam on the main shaft. These piston-valves of the cold pump are arranged as the former piston-valves, so as to close two ports on one side while opening those to the other, and vice versa. Ports 35 and 38 are respectively connected to the cold-spray nozzles 47 and 4:8 in the ends of cylinder C, and ports 36 and 37 terminate in the waste-openings -19 and in said cylinder. Ports 3E) and 42 are connected to and form the medium of supply of cold water from the cooler, and ports 40 and 41 are connected to and form the medium of return of the spent cold water to the cooler. The cooler is not shown, but may be of any form capable of cooling the water which has been used in cooling the working body of air in front of the piston during each of its strokes. In fact, on account of the peculiar construction of the Valves, no special cooler will be needed. The pump may simplydraw in cold water from a well or tank and eject it after use, allowing it to run to waste.

The connections of the pump-pistons and the piston-valves of both the hot and cold cylinders to the main shaft are not specifically shown, as various mcans of operation may be adopted, and the particular relations of the parts and their co-operativc movements will be understood by those skilled in the art from the following description of the operation, and I therefore purposely avoid unnecessary complication of the drawings in order to make the operation more clearly undcrstood.

Assuming that the high-pressure piston I has just started toward theleft while the lowpressure piston is just about to complete its stroke toward the right, and. bearing in mind that the piston-rods of both said pistons are connected to the main shaft by cranks at about ninety degrees apart, as shown in Fig. 5, the cycle of operations is as follows: When the piston P has passed the dead-center and has begun its return-stroke, the communicationvalve 8 is suddenly opened, valve 7 still remaining open. The high pressure behind piston P now is also imparted through the ports 6 and 10 to the piston P WVhen the former has reached the end of its stroke, all the air ahead of it will be in 'the cold cylinder, where it meets the cold spray from noz- 47 while being compressed therein; hence the detrimental effect which would be due to the heat generated in the air by the compressing action of the piston is entirely avoided by the presence of the cold spray, which abstracts such heat and leaves the air at its normal temperature. When piston P has reached the end of its stroke to the left, valve 7 is closed and the piston P of the cold cylinder has but a small amount of compression to effect. After the piston P of the hot cylinder has completed its stroke to the left hot spray is admitted from port 18 through nozzle 26 and immediately develops a high pressure in the body of air behind the piston P, thus driving it to the right. After the piston P has completed its stroke and its crankhas passed the dead-center the valve 7 is suddenly opened, and pressure is then also distributed over into cylinder C from cylinder H, and being behind the piston P drives it to the right. The opening and closing of the valves 7 and 8 between the two cylinders may be done at different periods from those already described. For the purpose of maximum eiiiciency I prefer to arrange them as follows: After the low-pressure piston P has completed about one-f0 u rt-h of its stroke the valve 7 is again closed for the rest of the stroke, and

expansion takes place with a very great chilling effect. This chilling, which would also take place in the high-pressure cylinder, is

Y prevented therein by the hot spray, which can be continued, if desired, for the whole stroke; hence the air is chilled in the lowpressure cylinder by its expansion, and when the cold spray is injected the cooling-liquidis made still colder, and this, in mixing with the liquid in the cooler, cools it also. Thus without needing a circulating stream of cold water outside the engine the engine itself, somewhat after the manner of an ice-machine,

provides its own cold liquid. The liquid is sprayed ahead of the piston P during its whole return-stroke, in order to take away the heat produced by the compression, and behind the same piston for a part of its forward stroke to cool the liquid. During part of the return-stroke the valve 7 is again opened, so that the heat produced by compression in the cylinder H may also be abstracted. Steam will expand to several thousand times its original volume before it falls in temperature to the freezing-point; but air in expanding to double its volume loses 17 0 Fahrenheit.

By the foregoing construction and operation it will be seen that the disadvantages hereinbefore referred to in this type of engine are completely eliminated. The hot sprays are thrown always and only into a hot cylinder into which no cold spray is admitted, while the cold sprays are always thrown into acold cylinder into which no hot sprays are admitted, and thus alternations of high and low temperature in the same mass of metal or cylinder are completely avoided. Another considerable advantage follows from the foregoing construction,in thatl obtain what may be termed a compound effect. Bearing in mind that the communication-valves 7 and 8 are arranged to be shifted to reverse position just after the piston of the cold cylinder-has passed the dead-center-that is, a little after the hot spray has begun to act in one end of the hot cylinder-this compound effect will be readily understood. It enables me to operate the hot cylinder under an extremely high pressure, wherein the full advantage of expansion may not be obtainable, and such expansion is then permitted to take place into the cold cylinder, and by action upon its piston helps to develop the power contained in the increment of heat imparted to the working body of air.

A highly important result follows from the arrangement of the various piston-valves in the ports connecting the heater and cooler, respectively, with their corresponding pumps and cylinders. As shown, the piston-valves hereinbefore described serve the purpose of absolute cut-offs in the communicating passages between the heater and the chamber containing the working body of air, as also between the cooler and the chamber containing the working body of air and between the heater and the cooler. This will be seen from inspection of Fig. 1, illustrating the hot connections, of which the cold connections for the cylinder are exact duplicates, as shown in Fig. 2. In Fig. l the pump-pistons 12 and 13 are moving to the right, and during their stroke the piston-valves 23 and 24 are stationary. Ports 1S and 19 are absolutely closed, cutting off all communication between the left-handpump-cylinder and the working-cylinder H. The ports 14 and 15 are, however, open, and as the piston 12 moves to the right it draws a fresh supply of hot water from the heater through the port 14 and drives back to the heater through the port 15 the spent hot water which has been used 011 the pre- Vious stroke of the piston P, through nozzle port 21 a fresh supply of hot water, which on the last stroke of the pump-piston 13 has been drawn from the heater through the port 17. The ports 16 and 17 are at this time closed by the piston-valve 24. It will therefore be seen that at no time is there any direct connection either between the hot cylinder and the heater or between the cold cylinder and the cooler orbetween the heater and cooler. The direct consequence of this is that I can, if desired, make use of avcry high initial pressure in the hotcylindenwhile usingonly a 1n oderate pressure in the heater and cooler, or either. As an illustration, I may heat the liquid-say waterin the heater to 327 Fahrenheit, at which temperature I need only have a superincumbent pressure of one hundred pounds per square inch on the surface of the water to prevent the latter from forming steam,and for the purpose of obtaining this super-incumbent pressure the water may be allowed to boil until the steam so formed produces the pressure in the dome or upper portion of the heater. If, now, I use an initial pressure in the cylinder of, say, five hundred pounds per square inch, 02 Fahrenheit being the normal temperature, the resultant pressure by spraying the water heated to 327 would be about fifty per cent. greater, or approximately seven hundred and fifty pounds per square inch, as the available initial pressure. Therefore the heater, having to sustain only a pressure of, say, one hundred pounds per square inch, may be made of comparatively light material with perfect safety, and the same can be said of the cooler.

The particular form of the cut-oif valves and the communication-valves is not of the essence of this invention, as they may be made and applied in a great variety of ways without departing from the principles on which my present invention is based.

For the purpose of regulation I use one of the ordinary forms of shaft-governor, whose eccentric is connected to the stem of a special form of valve, as illustrated in Fig. 6, which shows the relations of the hot-water pumps with the connections to and from the heater and to and from the hot-spray nozzles and waste-ports in the hot-cylinder. The piston-valves 22 and 24 are used, as in the previous instance; but the former is pro vided with the bypass i9. Above this piston-valve 22, which may in this case to advantage be in the form of a fiat slide-valve, a similarly-formed cut-off valve 50 is interposed, which is attached to the shaft-governor. The cut-off valve 50 has the ports 51, 52, 53, and 51, respectively, adapted to register with the ports 18, 19, 20, and 21. The cutoif valve 50' is formed with the bypass near one end and the by-pass 56 near the other end. The operation will be as follows: Should the amount of hot water thrown into the cylinder at any time become so great as to increase the working-pressure, and thereby tend to drive the engine faster in doing a given work, the shaft-governor operates to move the cutoff 50' into such position as to open communication between the ports 49' and the by-pass port 50, or at the other end of the cylinder with the bypass port 55. Referring to the right hand of Fig. 6, the effect is seen to be that instead of the entire amount of hot water being forced up through the hot spray 27 a portion of it passes through the port 49 into the port 56, thence through the other port 49' to the rear of piston 13, being compelled to take this path by the suction produced by the said piston in its movement toward the right; hence the quantity of spray is reduced, and with it the working-pressure, and by reason of the shaft-governor responding to changes of speed the action of: the cut-off valve 50 may be made such as to maintain a practically constant speed of the engine under all loads. Obviously the cutoff valve 50 as a movable part might be omitted and the slide-valve 22 connected to the shaft-governor instead, provided the bypass ports were still retained, in which event the ports 55 and 56 would be formed in the walls of the structure surrounding the slidevalve 22.

The foregoing automatic arrangement is also applicable to the cold pump and. cylinder to prevent the pressure getting too low and its operation and principles would be the reverse.

I have in my above-cited pending application described a means of automatic regulation wherein a by-pass is used between the hot-water pump and the cylinder; but the foregoing automatic devices differ from that shown in my said pending application in the fact that in the latter the water is not sent back to the heater 011 the return-stroke, as it is in this, but may be used as thespray in the other end of the cylinder.

The cooler and heater are not shown in the drawings, except in Fig. 7, but may be of any approved form. I prefer simply to use in both cases coils of pipe, the cooling-coil being submerged in cold water and the heatingcoil being subjected to a source of external heat. Obviously it does not make any difference whether these coils are beyond the pumps or between the pumps and the engine. If beyond the pumps, the hot or cold liquid will be drawn from them into the pumps. If between the pumps and the engine, then the liquid in the pumps will be forced through them and heated or cooled in transit, as the case may be. By the use of such pipes in some instances the valves 22 2t and 43 45 may be dispensed with, the pipes will readily stand any pressure the engine can safely stand, and shouldexplosion occur little damage would take place.

Fig. 7 illustrates diagram inatically the foregoing arrangement, in which the cold cylinder C and the hot cylinder H are arranged horizontally, as before, and have their respective pumps 30am] 11 on the side instead of below,

the cut-off valves 43 and 22 being, respectively, interposed between said pumps and their corresponding cylinders. A coil is arranged to be heated externally by any suitable means, and the discharge-ports 28 and 29 of the hot cylinder are connected to one end of coil 60 and the other end passes to the hot-water pump. The discharge-ports 49 and 50 of the cold cylinder 0 are connected to one end of the cooling-coil 61, which may be cooled by contact with the atmosphere or a tank of water, or any other suitable means of cooling the Water discharged from the cylinder 0. The other end of the coil 61 is connected to the cold pump. Thehot-water system is thus comprised in a sort of circuit including the coil-heater, the hot pump, and the working body of air in the hot cylinder. The coldwater system is comprised in a circuit including the cooler 61, the cold-water pump, and the body of working-air in the cold cylinder.

In some cases'for instance, small engines-Where simplicity more than economy is desired, good results may be obtained Without using the communicating valves between the hot and cold cylinders. In that event the ports 5 and 6 would be used and be always open.

I claim as my invention- 1. In a hot-air engine in which the working body of air is heated and cooled by the in troduction therein of hot and cold liquid, the combination therewith of meanssuch as a pumpfor forcibly withdrawing the spent heating or cooling liquid after its introduction.

2. In ahot-air engine in-which the working body of air is heated and cooled by the introduction therein of hot and cold liquid, the combination of a cylinder and piston for the direct development of power from air heated by the hot liquid, another cylinder and piston for the cooling of the air, and meanssuch as a pump or pumps-for forcibly withdrawing the spent heating and cooling liquids after their introduction.

3. In a hot-air engine in which the working body of air is heated and cooled by the introduction therein of .hot and cold liquid, the combination of a cylinder and piston having means for introducing hot liquid in contact with the working-air thereof, a cylinder and piston having means for introducing cold liquid in contact with its contained body of air, and means for transferring the body of air from cylinder to cylinder for submission to the hot and cold liquids, respectively.

4:. In a hot-air engine, the combination of a cylinder and piston provided with means for bringing the working bodies of air on the two sides of the piston into contact with separate bodies of hot liquid, a cylinder and piston provided with means for bringing the working bodies of air on the two sides of its piston into contact with separate bodies of cold liquid, and means for transferring the working bodies of air from cylinder to, cylinder for submission to the said hot and cold liquids, respectively.

5. In a hot-air engine in which the working body of air is heated and cooled by the introduction therein of hot and cold liquid, the combination of a cylinder and piston for the direct development of power from the air heated by the hot liquid, a cylinder and piston for the further expansion of the air from the first cylinder, at ported valve interposed between corresponding ends of the two cylinders, and means foropening and closing said valve intermittently.

6. In a hot-air engine in which the working body of air is heated and cooled by the introduction therein of hot and cold liquid, the combination of a cylinder and piston for the direct developement of power from air heated by the hot liquid, a separate chamber for cooling the working body of air with the cold liquid, and means for confining the body of air in said cylinder at the moment of contact with the hot liquid, and for subjecting such body of air to the cold liquid in said separate chamber.

7. In a hot-air engine in which the working body of air is heated and cooled by the introduction therein of hot and cold liquid from a heater and cooler, respectively, the combination, with the engine and heater and cooler, of interposed means for closing all communication between the engine and heater and cooler, while permitting liquid to be moved to or from either.

8. In a hot-air engine in which the working body of air is heated and cooled by the introduction therein of hot and cold liquid, the combination of a cylinder and piston for the direct development of power from air heated by the hot liquid, means for injecting hot liquid into the working body of air successively at opposite ends of said cylinder, an- I other cylinder and piston for the further expansion of the air from the first cylinder, and two ported valves respectively located and adapted intermittently to open and close communication between the respective ends of the two cylinders.

9. In a hot-air engine having one cylinder and piston for the direct development of power .from air heated by a hot liquid, and a cylinder for the further expansion of the air from the first cylinder, adapted to compress the working body of air before return to the first cylinder, the combination therewith of means for abstracting the heat of compression from the air before such return.

10. In a hot-air engine in which the pressure of the working body of air is intermittently reduced by the introduction thereinto of cold liquid, the combination therewith of a pump for forcing the cold liquid into such working body of air, an interposed regulating-valve adapted to vary the quantity of cold liquid admitted to the working body of air, and means dependent on the speed of the engine for operating said valve.

11. In a hot-air engine in which the working body of air is alternately heated and cooled by introducing therein hot and cold liquid alternately, the combination therewith of two pumps respectively adapted to throw hot and cold liquid into the working body of air, two regulating-valves respectively interposed in the delivery passages of said pumps and adapted to vary the quantity of hot and cold liquid admitted to the working body of air, and means dependent on the speed of the engine for operating both said valves.

12. In a hot-air engine in which the workin g-pressure is obtained by the introduction of heated liquid into the working body of air, the combination therewith of a pump for foreing the heated liquid into the working body of air, and an interposed variable cut-off valve dependent for operation on the speed of the engine and having in working relation a bypass adapted directly to connect the front and back of the pump-cylinder and afford a passage for excess oi": hot liquid.

13. In a hot-air engine, the combination of a working piston and cylinder provided with inlet and outlet ports for the ad mission and expulsion of a heating-liquid, a coil-heater containing the said liquid and communicating at its respective ends with said inlet and outlet cylinder-ports, and a pump interposed in the coil-heater system for producim the required movements of the heating-liquid.

14. In a hot-air engine, the combination of a working piston and cylinder-provided with inlet and outlet ports for the admission and expulsion of a heating-liquid, a working piston and cylinder provided with inlet and outlet ports for the admission and expulsion of a cooling-liquid, said cylinders having communication with each other, means for introducing cold liquid into one of said cylinders, a coil-cooler containing the cooling-liquid and communicating at its respective ends with the inlet and outlet ports 01: the latter cylinder, and a pump interposed in the coilcooler system for producing the required movements of the cooling-liquid.

15. In a hot-air engine in which movement of a piston is produced by a body of expanding air, the combination therewith of means for injecting into such body of air a spray of cold liquid, whereby the liquid is reduced in temperature by contact with the expanding air.

16. In a hot-air engine in which movement of a piston is produced by spraying hot liquid into the working body of air, the combination, with the engine, of an air-pump, an air tank or reservoir having a safety-valve, one or more eommun icatin g passages between the air-tank and the engine and provided with checkvalves, and means for maintaining said airpump in operation during the working of the engine.

17. In a hot-air engine having its working body of air at an initial normal pressure above that of the atmosphere, the combination therewith of a spraying device for hot liquid to in'lpart the Working-pressure, an air-pump, an air tank or reservoir provided with a safetyvalve or blow-cit, and means for maintaining said pump in operation during the operation of the engine.

In testimony whereof I a-fllx my signature in presence of two witnesses.

JAMES J. MCTIGHE.

\Vitnesses:

JAS. J. McAFnn, Tnos. M. BROWN. 

